Maca is the root-like hypocotyl of Lepidium meyenii, a plant of the mustard family (Brassicaceae) grown in the central Peruvian Andes at 4,000–4,500 m. It has been cultivated for food for about 2,000 years and has been sold worldwide since the 1990s, often as “Peruvian ginseng,” for libido, fertility, energy and menopausal symptoms (Gonzales, eCAM 2012; Beharry and Heinrich, J Ethnopharmacol 2018).

It is often grouped with “testosterone boosters,” but the trials do not support that label. In a 12-week randomized trial in healthy men, maca at 1.5 or 3 g/day did not change testosterone, LH, FSH, prolactin, 17-hydroxyprogesterone or estradiol, and later trials in men and women found the same (Gonzales et al., J Endocrinol 2003). The small trials that report benefits measured self-rated sexual desire, erectile function scores, mood and semen parameters, not hormones, and systematic reviews rate the evidence as limited.

This page summarizes what the clinical trials, systematic reviews and safety databases report. It is for education only and is not medical advice.

Property	Detail
Type	Food and herbal dietary supplement (root powder, gelatinized powder, extracts)
Plant	Lepidium meyenii Walp., family Brassicaceae; native to the central Andes of Peru
Main constituents studied	Glucosinolates (for example glucotropaeolin) and macamides (fatty-acid benzylamides)
Route	Oral
Doses used in trials	1.5–5 g/day of maca powder or extract, for 2–16 weeks
Half-life	No human pharmacokinetic data
Effect on testosterone	No change vs placebo in randomized trials in men
Liver safety	LiverTox: not linked to enzyme elevations or clinically apparent liver injury (one case report with a maca liquor)
US status	Sold as a food and dietary supplement; not listed as a controlled substance (21 CFR 1308.13)
WADA status	Not named on the WADA 2026 Prohibited List

What it is

Maca grows only in the high Andes, and people there eat the cooked, baked or fermented root. Since the late 1990s it has also become popular in China, where it is now grown widely, including in Yunnan province. Reviewers note that the shift to mass production, fertilizers and new growing regions may change the plant’s chemistry and so the content of commercial products (Beharry and Heinrich, 2018).

Products are sold by root color. The most common are yellow, red and black maca, and they differ in chemistry: in one trial’s spray-dried extracts, black maca had more fatty acids and macamides, while red maca had more GABA (Gonzales-Arimborgo et al., Pharmaceuticals 2016). “Gelatinized” maca is a heat-processed powder; it was used in several of the trials below.

Constituents

Compound group	What is known
Glucosinolates	Sulfur compounds typical of the mustard family. A USP-linked analysis of 42 maca root powders from 11 manufacturers identified four main glucosinolates: sinalbin, glucolepigramin, glucolimnanthin and glucotropaeolin (Xu et al., J Pharm Biomed Anal 2021)
Macamides	Benzylamides of fatty acids that are characteristic of maca. Several inhibited the enzyme soluble epoxide hydrolase in lab tests, and one, N-benzyl-linoleamide, was orally absorbed in rats (Singh et al., J Nat Prod 2020)
Nutrients	The root also contains fiber, amino acids, fatty acids, vitamin C, copper, iron and calcium (da Silva Leitão Peres et al., Food Funct 2020)

Proposed mechanism

How maca might affect sexual desire is not known. The effects in trials do not appear to work through sex hormones:

In healthy men, the rise in sexual desire was not explained by changes in testosterone, estradiol, or depression or anxiety scores (Gonzales et al., Andrologia 2002).
In postmenopausal women, water and methanol extracts showed no meaningful estrogenic or androgenic activity in a yeast-based hormone reporter assay (a lab test), even at high concentrations (Brooks et al., Menopause 2008).

Reviewers have proposed that macamides and glucosinolates cause the effects, but there are not enough data to confirm this (Beharry and Heinrich, 2018).

How it behaves in the body

We found no human study of how maca’s compounds are absorbed, metabolized or cleared, so it has no known half-life in people. The only pharmacokinetic data come from rats, where one isolated macamide (N-benzyl-linoleamide) showed “acceptable” oral pharmacokinetics (Singh et al., 2020). These results do not tell us how whole maca powder behaves in humans.

Effects on testosterone and other hormones

This is the most consistent finding in the maca trials: maca did not change reproductive hormones.

Trial	Participants	Dose and duration	Hormone findings
Gonzales et al., J Endocrinol 2003	Healthy men aged 21–56 (56 men, per LiverTox)	Gelatinized maca 1.5 or 3 g/day vs placebo, 12 weeks	No effect on LH, FSH, prolactin, 17-hydroxyprogesterone, testosterone or estradiol at 2, 4, 8 or 12 weeks
Gonzales et al., Andrologia 2002	57 healthy men aged 21–56	1.5 or 3 g/day vs placebo, 12 weeks	Testosterone and estradiol no different from placebo
Melnikovova et al., eCAM 2015	20 healthy men aged 20–40	1.75 g/day vs placebo, 12 weeks	No substantial change in hormone levels
Melnikovova et al., Phytother Res 2021	50 infertile men	2.8 g/day vs placebo, 16 weeks	No change in LH, FSH, prolactin, estradiol or total testosterone; free testosterone fell by 27% within the maca group
Shin et al., World J Mens Health 2023	80 men over 40 with symptoms of low testosterone but normal levels	Six 1,000 mg capsules/day (833 mg gelatinized maca each) vs placebo, 12 weeks	No difference vs placebo in total (p = 0.444) or free testosterone (p = 0.918)
Brooks et al., Menopause 2008	14 postmenopausal women (crossover)	3.5 g/day, 6 weeks each arm	No change in estradiol, FSH, LH or SHBG
Stojanovska et al., Climacteric 2015	29 postmenopausal women (crossover)	3.3 g/day, 6 weeks each arm	No change in estradiol, FSH, SHBG or TSH

In the 2023 Korean trial, total testosterone in the maca group was 4.40 ng/mL at baseline and 4.41 ng/mL at 12 weeks. The groups also differed at baseline (4.40 vs 5.46 ng/mL), which makes the comparison harder to read (Shin et al., 2023).

A 2024 systematic review of “testosterone booster” supplements included two maca studies. Maca was not among the few ingredients the authors rated effective or possibly effective for raising total testosterone (Morgado et al., Int J Impot Res 2024).

About “natural testosterone booster” claims. Maca is often marketed next to tongkat ali, tribulus, fenugreek, ashwagandha and D-aspartic acid. In the randomized trials above, maca did not raise testosterone in healthy men, in men with symptoms of low testosterone, or in infertile men. Any effect on libido reported in these trials happened without a hormonal change.

What the research shows

All of the human trials are small, most last 12 weeks or less, many use different products (powder, gelatinized powder, extracts of different colors), and several come from one research group in Peru whose senior author manages a company that makes nutraceuticals (Gonzales-Arimborgo et al., 2016).

Sexual desire

Trial	Participants	Dose and duration	Result
Gonzales et al., 2002	57 healthy men (30 on 1.5 g, 15 on 3 g, 12 on placebo, per Shin et al. 2010)	1.5 or 3 g/day, 12 weeks	Self-rated sexual desire improved from week 8; effect independent of mood, anxiety and hormones
Stone et al., J Ethnopharmacol 2009	8 trained male cyclists (crossover)	Maca extract, 14 days	Sexual desire score higher than with placebo (p = 0.03); 40 km time-trial not better than placebo
Gonzales-Arimborgo et al., 2016	175 adults at low and high altitude	3 g/day red or black maca extract, 12 weeks	About 50% on red maca reported more desire at week 12; difference vs placebo significant only at high altitude (p = 0.03)

The Shin et al. systematic review re-analyzed the 2002 trial data and found a mean difference in sexual desire of 1.64 points (95% CI 1.07–2.21) at 8 and 12 weeks, but no difference at 4 weeks (Shin et al., BMC Complement Altern Med 2010).

Erectile function

In 50 Italian men with mild erectile dysfunction (ED), maca dry extract at 2,400 mg/day for 12 weeks raised the IIEF-5 score (a 5-question erectile function questionnaire scored 5–25) by 1.6 ± 1.1 points, vs 0.5 ± 0.6 with placebo (p under 0.001) (Zenico et al., Andrologia 2009). The authors called this a “small but significant effect” on subjective well-being.

In the 2023 Korean trial of 80 men over 40 with low-testosterone symptoms (Shin et al., 2023):

Outcome at 12 weeks	Maca (n = 41)	Placebo (n = 39)	p (between groups)
Aging Males’ Symptoms score (lower is better)	45.6 → 35.0	47.8 → 48.6	under 0.0001
IIEF total score (higher is better)	33.2 → 47.2	31.3 → 26.0	under 0.0001
IPSS urinary symptoms (lower is better)	13.9 → 11.6	13.2 → 14.6	0.0001

Scores in the placebo group got worse over the trial, which widened the gap between groups. Several authors listed affiliations with health-product companies (Yuhan Care and Green Medicine).

Systematic reviews of herbal supplements for ED rate the maca data as “very preliminary” (Borrelli et al., Drugs 2018) and “insufficient” (Ho et al., J Tradit Complement Med 2026). In both reviews, ginseng showed a pooled benefit on erectile function.

Two trials from Massachusetts General Hospital tested maca in people whose sexual function was impaired by SSRI or SNRI antidepressants:

Dose-finding pilot. 20 patients (17 women) were randomized to 1.5 or 3 g/day. Only the 3 g/day group improved significantly on two sexual function scales. There was no placebo arm (Dording et al., CNS Neurosci Ther 2008).
Placebo-controlled trial. 45 women received 3 g/day or placebo for 12 weeks. The mean change in sexual function scores was not significantly different from placebo. Remission rates were slightly higher with maca (for example 9.5% vs 4.8% by one scale), with the difference driven by the 12 postmenopausal women (Dording et al., eCAM 2015).

Semen parameters

Trial	Participants	Dose and duration	Result
Gonzales et al., Asian J Androl 2001	9 healthy men (no control group)	1.5 or 3 g/day, 4 months	Semen volume, sperm count and motility rose; hormones unchanged
Melnikovova et al., 2015	20 healthy men	1.75 g/day, 12 weeks	No significant difference vs placebo; authors reported “rising trends”
Alcalde and Rabasa, Andrologia 2020	69 men with mild low sperm count or motility	2 g/day, 12 weeks	Sperm concentration higher with maca (mean 15.04 vs 10.16, p = 0.011); no difference in volume, motility or morphology
Melnikovova et al., 2021	50 infertile men (39 completed)	2.8 g/day, 16 weeks	Sperm concentration rose 40% with maca and 76% with placebo; not significant

A 2022 meta-analysis pooled the randomized trials in infertile men. Maca did not increase sperm concentration compared with placebo (weighted mean difference 2.22, 95% CI −2.94 to 7.37, p = 0.4), with very high heterogeneity between trials (I² = 91%). In the authors’ re-analysis of the 2015 trial in healthy men, sperm concentration was actually lower with maca than placebo. The review concluded that maca’s effects on semen quality are “unclear” (Lee et al., Front Pharmacol 2022). An earlier 2016 review, which also counted uncontrolled studies, had called the evidence “suggestive” (Lee et al., Maturitas 2016).

Mood, energy and menopausal symptoms

In 14 postmenopausal women, 3.5 g/day for 6 weeks lowered Greene Climacteric Scale scores for anxiety, depression and sexual dysfunction compared with placebo (Brooks et al., 2008).
In 29 postmenopausal Chinese women, 3.3 g/day for 6 weeks lowered depression scores and diastolic blood pressure (Stojanovska et al., 2015).
In 175 Peruvian adults, 3 g/day of red or black maca extract for 12 weeks improved self-rated mood, energy and health-related quality of life compared with placebo; red maca did better on mood and energy (Gonzales-Arimborgo et al., 2016).

A 2011 systematic review found four small randomized trials on menopausal symptoms, all favorable, but judged the number, size and quality of trials too limited for firm conclusions (Lee et al., Maturitas 2011).

What the systematic reviews conclude

Review	Topic	Trials included	Conclusion
Shin et al., 2010	Sexual function	4 RCTs, 131 participants	“Limited evidence”; no trial reported its randomization method or assessed side effects
Lee et al., 2011	Menopausal symptoms	4 RCTs	Limited evidence; safety not established
Borrelli et al., 2018	Erectile dysfunction	1 maca RCT (n = 50)	Very preliminary positive result
Lee et al., 2022	Semen quality	5 RCTs	No pooled effect on sperm concentration; effects unclear
Morgado et al., 2024	Testosterone	2 maca studies	Not rated effective for raising testosterone
Ho et al., 2026	Erectile dysfunction	14 RCTs of herbs	Evidence for maca insufficient

Side effects and risks

Tolerability in trials

Maca has been well tolerated in the short trials, but most of them did not collect side-effect data carefully. Both the 2010 and 2022 systematic reviews noted that the included trials did not try to assess adverse effects (Shin et al., 2010; Lee et al., 2022). What has been reported:

175 adults, 12 weeks, 3 g/day: no serious adverse effects, and no one stopped because of a side effect (Gonzales-Arimborgo et al., 2016).
80 older men, 12 weeks: two men on maca had mild stomach and bowel complaints; no clinically significant changes in lab tests or vital signs (Shin et al., 2023).
45 women on antidepressants, 12 weeks: three stopped for adverse events such as flu-like symptoms and vomiting that the authors found hard to attribute to maca; liver tests were not measured (Dording et al., 2015).

Liver

LiverTox, the US National Institutes of Health database on drug-induced liver injury, states that maca has not been implicated in serum enzyme elevations or clinically apparent liver injury. It lists one case report: a 30-year-old man in China developed jaundice a few days after drinking 300 mL of a “maca medicinal liquor” and recovered over 1–3 months (LiverTox; Xiao et al., Chin Med J 2017).

Blood pressure

Findings conflict. In a 90-day trial in people with metabolic syndrome, the maca-only group (0.6 g/day) had a moderate rise in the liver enzyme AST and in diastolic blood pressure (Valentová et al., Food Chem Toxicol 2008). In contrast, diastolic pressure fell in the Hong Kong trial (Stojanovska et al., 2015), and blood pressure did not change vs placebo in the 175-person Peruvian trial (Gonzales-Arimborgo et al., 2016).

Interactions

We found no clinical drug-interaction studies. In a lab model of human intestinal tissue, a commercial maca product inhibited the drug-metabolizing enzyme CYP3A by less than 50%, unlike green tea extract or St. John’s wort, which inhibited it by over 80% (Loretz et al., Drug Metab Dispos 2020). A retrospective review of 1,816 adverse-event reports linked one case of restless legs syndrome to maca taken with the antidepressant mianserin (Siwek et al., Front Pharmacol 2023).

Who has no safety data

We found no trials of maca in pregnancy, breastfeeding, children or people with liver or kidney disease. The longest controlled trials lasted 16 weeks.

Quality and contamination

Variable content. Products differ by color, origin, processing and growing method, and there were no standard test methods for maca until compendial (USP) methods for glucosinolates were proposed in 2021 (Xu et al., 2021). In one analysis, only certain commercial products contained macamides at the levels the authors considered biologically relevant (Singh et al., 2020).
Heavy metals. Maca grown near mining areas in Junín, Peru, contained cadmium (0.32 mg/kg) and lead (0.20 mg/kg) above FAO/WHO limits. Estimated non-cancer risk was low, but the estimated cancer risk from arsenic and cadmium exceeded the tolerable limit for local consumers (Orellana Mendoza et al., Toxicol Rep 2021).
Trial products are not store products. Results from one gelatinized powder or one red-maca extract may not apply to other products.

Key takeaways

An Andean root vegetable, not a hormone. Maca is a mustard-family food crop sold as a supplement for libido, fertility and energy.
No effect on testosterone. Randomized trials in healthy men, infertile men and older men with low-testosterone symptoms found no rise in testosterone or other reproductive hormones vs placebo.
Small, possible effects on desire and erections. A few small trials reported better self-rated sexual desire and modestly better erectile function scores, but reviews call the evidence limited or insufficient.
Semen results are inconsistent. A 2022 meta-analysis found no pooled effect on sperm concentration in infertile men.
Generally well tolerated in short trials. No liver injury pattern is recognized, but side effects were rarely measured carefully and no trial lasted over 16 weeks.
Product quality varies. Content differs by color, origin and processing, and maca grown near mines can carry heavy metals.

Sources

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